Does Organization in Turbulence Influence Ozone Removal by Deciduous Forests?

Dry deposition is an important sink of tropospheric ozone and influences background and episodic ozone air pollution. Plant canopies remove ozone through uptake by plant stomata, leaf cuticles, and soil. Stomatal uptake of ozone injures vegetation, thereby altering local‐to‐global water and carbon cycling. Observed ozone fluxes are used to inform dry deposition parameterizations in chemical transport models but represent the net influence of several poorly constrained processes. Advancing understanding of the processes controlling dry deposition is key for building predictive ability of the terrestrial ozone sink and plant damage. Here, we constrain the influence of spatial structure in turbulence on ozone dry deposition with large eddy simulation coupled to a multilayer canopy model. We investigate whether organized turbulence separates areas of efficient leaf uptake from areas of high or low ozone mixing ratios. We simulate summertime midday conditions at three homogenous deciduous forests with varying leaf area, soil moisture, and ambient humidity. Sensitivity simulations perturb atmospheric stability, parameters related to ozone dry deposition, how quickly stomata respond to local atmospheric variations, and entrainment of ozone from atmospheric boundary layer growth. Overall, we find a low covariance between ozone and leaf uptake, in part due to counteracting influences from micrometeorological variations on ozone and leaf uptake individually versus the influence of leaf uptake on ozone. The low covariance between ozone and leaf uptake suggests that dry deposition parameterizations and interpretations of ozone flux observations can ignore the influence of organized turbulence on dry deposition. Plain Language Summary The atmospheric boundary layer (the part of the atmosphere closest to the earth) organizes itself into structured air motions that vertically transport momentum, energy, and gases toward and away from the Earth's surface. Using computer simulations with very high spatial resolution, we examine the relationship between these organized motions and a forest canopy. All of the leaves in the forest in our simulations are represented by the same biological and physical processes, but the variables modifying these processes (e.g., temperature, wind, humidity) vary spatially as the result of the organized air motions. Ozone, a gaseous air pollutant, also varies as the result of the organized air motions. Because removal of ozone from air through